This bulletin applies to 2016-2019 Chevy Corvette models equipped with a 6.2L LT1/LT4/LT5 engine. The SES lamp may be on and rich running condition DTCs P0172 and P0175 may be stored. The possible cause involves the high pressure fuel pump.
Disconnect the dirty air side of the PCV system. Plug the vacuum supply. Start the engine and monitor fuel trims in closed loop. If the fuel trims return to normal, this is a good indicator that the high pressure fuel pump is leaking. According to the GM bulletin, “with this concern, we do not see a lot of fuel in the crankcase, so changing the oil may not isolate the concern.”
When the high pressure fuel pump leaks, the PCV will pull the fuel mist straight into the intake, causing the concern. According to the release, “this is a preliminary temporary diagnostic and repair.”
The bulletin noted that as more investigation becomes available GM will update this bulletin.